The present invention relates to organosilicon compounds containing dioxolane, diol or diacrylate radicals and to methods for their preparation and use. More specifically, the present invention relates to polymerizable organosilicon compounds, containing one or more silicon-bonded diacrylate radicals, which are prepared from silicon hydride compounds via novel intermediates, and to the use of those polymerizable organosilicon compounds to provide a substrate with a cured coating.
The preparation of organosiloxane compounds containing one or more pendant diol radicals has been suggested by Okazaki et al., U.S. Pat. No. 4,431,789. However, the suggested synthesis method for these compounds comprises the hydrosilylation of an aliphatically unsaturated diol compound with a siloxane hydride. In view of the ready reaction of silicon-bonded hydrogen atoms with alcoholic groups, as well as with aliphatic unsaturation, under such reaction conditions it is likely that a considerable amount of crosslinking occurs, by way of SiOC bond formation and SiC bond formation, and that hydrolyzable gels would be obtained by this method. While the presence of hydrolyzable gels may not be of any substantial consequence for the purposes of patentees, said gels are unacceptable when one desires to use the product as a component in a coating composition.
Organosiloxane-silicate copolymers containing silicon-bonded diol radicals have been disclosed by Pines et al., U.S. Pat. No. 3,337,496. The synthesis route suggested by patentees makes use of silanes which contain epoxy group-containing radicals, said radicals being changed to diol radicals when the silane is hydrolyzed and condensed to form the siloxane-silicate copolymers. The epoxy-containing silanes are said to be available via a hydrosilylation reaction between an aliphatically unsaturated epoxide and a silane hydride. However, the hydrosilylation of epoxides, such as allyl glycidyl ether, is not a straightforward reaction.
On the one hand the hydrosilylation of epoxides with chlorosilanes to provide epoxide-substituted silanes is impossible because of the reaction of the silicon-chlorine linkage with the epoxide ring, as shown by Lavigne et al.; J. Organometal. Chem., 15, 57(1968).
On the other hand the basic nature of the epoxide group tends to poison the usual metal catalysts that are used to promote said reaction and tends to cause a disproportionation reaction to occur with the various hydrolyzable groups that are bonded to the silicon atom of the silane. While it may not be important for patentees' intended use it is unlikely that this synthesis route would lead to diol silanes and siloxanes suitable for the preparation of coating compositions.
Kotzsch et al., U.S. Pat. No. 3,825,567, has addressed the above-noted problems associated with the hydrosilylation of epoxides by hydrosilylating an aliphatically unsaturated dioxolane containing 2,2-dihydro or 2-oxo substitution with a silane hydride and converting the resulting dioxolane-containing silane to an epoxy-containing silane. However, patentees do not suggest any other 2,2-disubstituted dioxolanes or that the dioxolane-containing silanes are useful for preparing diol-containing silanes and siloxanes.
Beckmann et al., U.S. Pat. No. 4,303,739, discloses 4-(methyl-3'-(trimethoxysilyl)-propoxy)-1,3-dioxolane and its use in the preparation of laminated safety glass. Its synthesis is not specifically disclosed and its conversion to an diol-containing silicon compound is not suggested.
Acrylated silicones have been formulated by Watson et al., U.S. Pat. No. 4,331,704, into a radiation-curable varnish for application to uncured, oil-based ink products. While many acrylated silicones, including monoacrylate-monool containing silicones, are referred to by patentees as being suitable for their radiation-curable varnishes, diacrylate-containing silicones are not disclosed or suggested.